To obtain a considerably useful substrate capable of replacing silica gel as an ion exchange resin, a column filler for the liquid chromatography, a solid phase for solid phase extraction and a reaction matrix.

The spherical resin comprises a polymer having a basic unit structure represented by formula (I) (wherein R1 is carboxylic group or hydroxymethyl group, or two R1s are linked together to form CO-O-CO; R2 is a 2-8C divalent saturated hydrocarbyl group; and (n) is a number of 1-6). The spherical resin is characterized in that it is a substrate exhibiting extremely high hydrophilicity compared with a maleic anhydride-based spherical resin obtained by using as acrosslinking agent such as divinylbenzene, 1,7-octadiene, that it is sufficiently stable over a wide pH range compared with silica gel because it is an organic polymer, and that it is a substrate having a weak interaction with a hydrophobic substrate compared with silica gel and therefore exhibits extremely high hydrophilicity.